Mirage.—The phenomenon known as mirage has been classed as follows by scientists: 1—The mirage of the desert; 2—the mirage of the sea; 3—looming; 4—a combination of the 2d and 3d; and 5—the Fata Morgana. The first has been frequently witnessed on the Western plains in the United States. It is due to the refraction of rays of light passing through strata of air of unequal density, and may be illustrated by the following simple experiment: Place a small coin in a shallow opaque vessel and take a position where the edge of the coin is just visible. Then have an assistant pour clear water into the vessel and in a short time the whole coin can be seen. The density of the water being greater than that of the air, the line of vision is refracted or bent downward, bringing the coin into view. So, in like manner, a ray of light may be bent in passing through layers of air of diffeernt[sic] density, bringing into view distant objects below the horizon. The Herald of Freedom of Feb. 17, 1855, gives the following description of a mirage seen in Kansas:

"On yesterday we had the privilege of seeing a rare sight—a mirage on the prairie. On approaching the town of Lerny, about a mile and a quarter this side, we found the whole intermediate space between us and the grove of trees beyond the town apparently occupied by a beautiful lake of water. On the apparent shores next to ourselves the road ran down and disappeared in the lake, as did the fence upon one side of the road, while the placid and beautiful water extended upon the right and left, until lost in the distance. The trees in the distance appeared to be immersed for half their length in the lake, as if growing in the water. Even the reflection of the trees, and of the clouds above, were distinctly visible. We approached the vision and it vanished."

Frank P. Root, in his History of the Overland Stage (p. 251), describes a mirage he once witnessed. Says he: "In connection with my first trip by overland stage coach, I witnessed a grand and beautiful sight that I shall never forget. It was late in the afternoon of Jan. 27, 1863, in the South Platte valley, between Alkali lake and old Julesburg, upwards of 400 miles west of the Missouri river. The air was cool, but the sun shone with dazzling brilliancy. Sitting on the box with the driver, as we were making good time up the valley, suddenly, a few miles beyond us to the west, there loomed up in the distance something that appeared to resemble a lake. Going a short distance farther, the scene changed, and there appeared a number of buildings, only they were above the horizon and inverted, it was one of the strangest and, to me, one of the grandest sights I had ever beheld."

Numerous instances of this character have been recorded, and in some cases the mirage has been so perfect that the town or object brought into view has been recognized. As the "Great American Desert" has been brought under cultivation mirages have become less frequent, though they are still sometimes seen in the western part of Kansas and Nebraska, and at other places on the sparsely settled plains.